Generally ordinary bolts and nuts can be easily used for fastening ordinary structures where access is available to both sides. In such a case, the bolt can be inserted easily from the other side of a plate or other structure. However, in the case where the other side of the structure is hidden or closed to bar access for the hands of people or tools to the other side, it is impossible to fasten an item to the structure with ordinary means.
Korean Patent Publication No. 90-221 which is granted to the present Applicant discloses a solution to the above problem, in which a circular washer is divided into two pieces or into a plurality of pieces, and each of the pieces is connected to two pulling strings. The divided pieces are inserted one by one into a fastening hole, and then the strings are pulled out, so that the divided pieces are assembled into a circular washer at the other side of the fastening hole. In practice, the head portion of a bolt is inserted into the fastening hole, and then the strings are pulled out to assemble the divided washer at the other side of the hole, and to make the assembled washer to support the head of the bolt. However, in this prior device, while it is convenient to insert the divided washer pieces into the fastening hole one by one, there is the limitation that the fastening hole has to be larger than the head of the bolt if a fastening is to be carried out. Further, a divided washer is necessarily involved.
There is another related device disclosed in U.S. patent application Ser. No. 303,354, and in the device of the present invention in which a pulling string is attached to the lower portion of a bolt, while pieces of an elongate oval washer divided into narrow pieces are inserted into a fastening hole one by one. Then the pulling string is pulled out so that the assembled washer supports the head of the bolt. Then a nut is fastened to the forwardly projected tip of the bolt, and therefore, this device also requires the condition that the fastening hole is larger than the head of the bolt. It is a principal object of the present invention to overcome the above described limitations of conventional devices.
It is a further object of the invention to provide a fastening device in which the head of a bolt as large as a washer is supported directly at the distal side of a fastening hole.
It is a further object of the invention to enable a hole in the structure not substantially larger than the device's minimum cross section.
Further objects of the invention are to provide a fastening device in which tightening can be carried out with a collar instead of a nut by providing a locking groove, or a riveting can be used by bending the tip of the bolt.